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Frequent Internet drops due to SYNC timing failure, T3 & T4 time-outs

Frequent Visitor

Frequent Internet drops due to SYNC timing failure, T3 & T4 time-outs

Hello,

I am experiencing almost daily internet outages from SYNC timing failures, T3 time-outs and T4 time-outs. I am an internet-only customer with a brand new drop of RG-11 coax (approx. 200') directly to a line-amp up on the pole. No splitters in the path directly to my modem (Motorola MB8600, DOCSIS 3.1). During the outage I attempt to reset the modem via the mobile app but that does not work so I end up having to manually cycle power to the modem to get the service back up. My signal levels (when service is up) are excellent – see below however my Corrected/Uncorrected numbers are very high which would suggest intermittent upstream problems.

This is very frustrating and I am cringing at the thought of having to have multiple call-outs and dealing with technicians who have no idea of how to properly troubleshoot…

Frequent Visitor

Re: Frequent Internet drops due to SYNC timing failure, T3 & T4 time-outs

Update:

Over 500,000 corrected in 24 hrs...

Motorola MB8600 troubleshoot.jpg

Expert

Re: Frequent Internet drops due to SYNC timing failure, T3 & T4 time-outs

@azdeltawye

 

I've asked an employee to check the CMTS for real-time and historical RF signal reports from your modem. They can also check your local node/plant for any degradation or error reports. You can expect a reply in this thread. 

 

While you wait for a response, you may want to do some troubleshooting on your own: See the troubleshooting guide.

Frequent Visitor

Re: Frequent Internet drops due to SYNC timing failure, T3 & T4 time-outs


@nerdburg wrote:

@azdeltawye

 

I've asked an employee to check the CMTS for real-time and historical RF signal reports from your modem. They can also check your local node/plant for any degradation or error reports. You can expect a reply in this thread. 

 


@ nerdburg - Thanks for looking into this!!

 

I'm going through the motions and scheduled a premises technician to come out this weekend. Hopefully he can elevate the ticket from his end.

 

Good thing I have the 3.1 modem as it appears all my traffic is being carried by the OFDM channel...

Official Employee

Re: Frequent Internet drops due to SYNC timing failure, T3 & T4 time-outs

Hi, azdeltawye - If you'll still have issues after the upcoming tech visit, please let me know and I will investigate your case. Thank you!

Frequent Visitor

Re: Frequent Internet drops due to SYNC timing failure, T3 & T4 time-outs

Update: Since my last post I have had two Comcast Premises Technicians visit my house to troubleshoot this issue. Both technicians checked out and verified that my drop, home wiring and modem are all ok and functioning properly. The second technician thought my upstream power levels were a bit low so he installed a 3 dB attenuator on the back of the modem. As expected, this reduced my downstream and increased my upstream signal strength by the same amount. However, this had no effect on addressing the root cause of the problem. Unfortunately, since this is an intermittent problem, both technicians were there at a time when the system was running clean and could not see anything that was out of spec or problematic…

I have made a few key observations that maybe helpful:

  • The majority of dropped connections and T3 timeouts seem to occur at 19:45 – 20:00hrs.
  • Multiple dropouts have occurred around 10:00 am as well.
  • The dropouts seem to be related to heat and appear happen more frequently when average ambient temperature is above 85 deg. F. (highs in the 100’s).
  • Zero corrected or uncorrected codewords on the OFDM (DOCSIS 3.1) channel.

 

Here is a current screen shot of modem connection signal statistics. Notice the high ratio of uncorrected to corrected codewords:

 

Capture.PNG
Expert

Re: Frequent Internet drops due to SYNC timing failure, T3 & T4 time-outs


@azdeltawye wrote:

The second technician thought my upstream power levels were a bit low so he installed a 3 dB attenuator on the back of the modem. As expected, this reduced my downstream and increased my upstream signal strength by the same amount. However, this had no effect on addressing the root cause of the problem. s:

 


FWIW, and as an FYI, that doesn't work for the upstream power. It only makes it look prettier as read at the modem. The power received at the node and the CMTS is still the same. However it does indeed work to lower the downstream power.

Official Employee

Re: Frequent Internet drops due to SYNC timing failure, T3 & T4 time-outs

Hi, @azdeltawye - There is an open maintenance order for node health in your area. It's in Suspended status. As I mentioned in my private message, we need to schedule another tech visit. Otherwise, I won't be able to escalate any further. Since you've mentioned that dropouts had occurred around 10:00 AM - we can schedule a tech visit appointment around 10:00 AM. 

Frequent Visitor

Re: Frequent Internet drops due to SYNC timing failure, T3 & T4 time-outs

So it appears they have fixed the problem that I was experiencing with the T3 timeouts and intermittent upstream connectivity.  I have not had any outages in the last 10+ days! Additionally, my corrected and uncorrected codeword counts have not increased since my last post on 6/18... Over the past week I have noticed seeing a couple Comcast bucket trucks in and around my neighborhood doing work.

 

Even though my problem seems to be fixed now I am a little annoyed that I never received any communication from Comcast saying that they were working on the problem nor did I receive any awknologement that there was any problem at all...

 

I guess that I should just be thankful that the problem is fixed and leave it at that...

Official Employee

Re: Frequent Internet drops due to SYNC timing failure, T3 & T4 time-outs

@azdeltawye - We don't notify customers about the maintenance work in the area. However, back on June 11th, I did let you know that there is a maintenance order in your area and there are issues with RF signals. I also originally reached you here, in this thread, on June 4th and haven't received a message back until June 11th. Tier 1 agents won't have information regarding the maintenance work in your area, the simply don't have an access. If in the future you will get any issues - please feel free to reach me or my team at any time. 

Frequent Visitor

Re: Frequent Internet drops due to SYNC timing failure, T3 & T4 time-outs

 

 


@ComcastElla wrote:

@azdeltawye - We don't notify customers about the maintenance work in the area. However, back on June 11th, I did let you know that there is a maintenance order in your area and there are issues with RF signals. I also originally reached you here, in this thread, on June 4th and haven't received a message back until June 11th. Tier 1 agents won't have information regarding the maintenance work in your area, the simply don't have an access. If in the future you will get any issues - please feel free to reach me or my team at any time. 


Thanks for the response. I really do appreciate the follow-up..